1. Field of the Invention
This invention relates to a video signal processor which is suitable for use in a video tape recorder for public use or the like, and specifically to a video signal processor which is suited to add or insert binary-coded signals such as time codes in a vertical blanking period and/or to read the same.
2. Description of the Related Art
Commercial video tape recorders already use time codes expressed by time, minutes, seconds and the number of frames which have been binary-coded inserted in a vertical blanking period of video signals to designate a tape location (address) by using such time codes. The term, "time codes" are generally called "VITC" (Vertical Interval Time Code). This has been introduced on, for example, pages 226 to 228 of the technical journal "VTR Technology" compiled by NHK (Nippon Hoso KyoKai).
As signals to be inserted in the vertical blanking period, codes or the like, which are indicative of the number of frames used for a character broadcasting or a laser disk, are used as an alternative to the VITC signal. In addition, plans to insert a reference signal for ghosting cancellation, i.e., a ghost canceller (which will hereinafter be called a "GCR") in the vertical blanking period, have been brought forward; practical testing for broadcasting purposes is already being conducted.
There are some cases, for example, where a period during which these information signals are inserted in the same period during which the time codes are inserted or is subsequent to a period during which the time codes are inserted within the vertical blanking. Accordingly, where it is desired to apply time codes to the video tape recorders or to the videotapes themselves for public use, there is a possibility of these signals being combined with those within the period of the vertical blanking. Consequently, there is risk of malfunction in time coded reading.